Fertilizing Stone Fruits

This is our fertilizer program for stone fruits - peaches, plums, nectarines, pluots, plumcots, apriums, apricots and cherries. We recommend reading our page Fertilizing Fruit Trees, which discusses some general and useful information about fruit nutrition.

How much to apply
Stone fruits need approximately 1/8 lb of nitrogen per year, per inch of trunk diameter, as measured 12" above grade. Too much nitrogen prompts excessive vegetative growth. The goal is to only replace the nitrogen the tree uses every year and to focus on the overall health of the soil, not to artificially support the tree.

To calculate how much to apply:

Using a flexible tape measure (seamstresses tape), measure the circumference of the tree 12" above grade.

Divide the result by 3 (it is actually 3.14, or pi, but 3 is close enough). The result is the approximate diameter (caliper).

Multiply the diameter x 0.125. The result is the number of pounds of nitrogen the tree requires each year (not each application).

If the circumference of the tree is 6", the diameter is approximately 2". Therefore, you will need 0.25 lb (1/4 lb) of nitrogen (2 x 0.125). To determine how many pounds of fertilizer you will need to apply to deliver 0.25 lbs of actual nitrogen, divide the required pounds of nitrogen by the percent of nitrogen in your slow release organic fertilizer. The nitrogen content is indicated by the first number in the three digit code on the bag (N-P-K).

For example, if your tree requires 1/4 lb of nitrogen, and your SROF is 4-4-3, you will apply approximately 6.25 lbs of that fertilizer for the year. If you are using an SROF with a formula of 6-2-4, you will apply 4 lbs of fertilizer for the year.

4-4-3: .25 / .04 = 6.25# 6-2-4: .25 / .06 = 4.17#

When to apply
There are different philosophies on how often fertilizer should be applied to stone fruits, but all agree that they prefer frequent small amounts rather than one or two large applications. Remember that the amount you calculated is an annual amount required. Divide the number of pounds you calculated by the number of applications you will use.

Because we use only slow release organics, and because it suits our schedule, we apply it in (3) applications - February (at bud break), May, and August. If it fits in your schedule, you can apply it in (4) applications - February (at bud break), April, June, and August. Do not fertilize after August.

Slow release organic fertilizers include minerals and mycorrhizal fungi. It is not necessary to apply them separately. They also contain dried molasses, but I often apply a few extra handfuls because it is such a good microbial food.

How to apply
Broadcast the fertilizer in a radial band around the tree, starting approximately 8" - 12" from the trunk and extending to the drip line or slightly beyond. Feeder roots are not concentrated close to the trunk, but they often extend beyond the drip line.

It is not necessary to cultivate the fertilizer into the soil, but it is more effective if it is in contact with the soil where soil microbes can begin to process it. After the first application each year, apply an inch or so of compost over the root zone, then apply mulch. Regular use of high quality compost and organic mulches will reduce your fertilizer requirements over time.

Stone fruits are generally quite vigorous, but if the tree is overly vigorous, cut back the amount of fertilizer by 20% - 25% the following year and observe the response. Excess vigor will produce vegetative growth and wood that has more leaf buds and few fruit buds.